class Solution {
public:
    int minDistance(string word1, string word2) {
        // Start typing your C/C++ solution below
        // DO NOT write int main() function
		int n = word1.length();
		int m = word2.length();
		vector<vector<int> > dp(n + 1, vector<int>(m + 1));

		for (int i = 1; i <= n; ++i) {
			dp[i][0] = i;
		}
		for (int j = 1; j <= m; ++j) {
			dp[0][j] = j;
		}
		for (int i = 1; i <= n; ++i) {
			for (int j = 1; j <= m; ++j) {
				if (word1[i - 1] == word2[j - 1]) {
					dp[i][j] = dp[i - 1][j - 1];
				} else {
					dp[i][j] = dp[i - 1][j - 1] + 1;
				}
				dp[i][j] = std::min(dp[i][j - 1] + 1, dp[i][j]);
				dp[i][j] = std::min(dp[i - 1][j] + 1, dp[i][j]);
			}
		}
		return dp[n][m];
    }
};